Spectra of W Aql as observed using HIFI. The top right corner of each spectrum gives the frequency setting within the HIFISTARS project. Strong lines are labelled with their corresponding molecule identification. The spectra are obtained in double sideband mode, and the lower sideband (LSB) and upper sideband (USB) frequencies are given below and above the spectra, respectively. The spectra are corrected for baseline effects (see text). The intensity scale is given in main beam brightness temperature.